The present invention relates to an assembly for retaining a caster mounted on a shaft on a support structure, e.g. the leg of a sofa.
In accordance with the prior art, casters have typically been connected to the legs of various pieces of furniture by the use of a mounting member having a serrated edge. Such an arrangement is shown in FIG. 1 of the drawing. As illustrated, a caster 2 is to be secured to a leg 4, such as the leg of a sofa or a stretcher for a sofa. Actually, the caster is secured within opening 8 in end face 6 of the leg. Caster 2 includes a roller 18, a support 20 for rotatably supporting the roller, and ball bearings 16 which rotate in a disk-like member 17 and enable support 20 to be rotatable about the longitudinal axis of a mounting shaft 11. Shaft 11 has a knob-like locking member 13 at its lower end. The caster is secured to mounting sleeve 10 that has two sleeve elements and a serrated retainer 12. The two-part sleeve 10 can be easily inserted into the bore hole but once shaft 11 is inserted, the two parts are spread apart thereby providing a force against the removal of the caster assembly.
In utilizing the above-described caster assembly, first sleeve member 10 is inserted into hole 8 and retainer 12 is seated with a mallet. Then shaft 11 of caster 2 is inserted into sleeve member 10 and also tapped with a mallet to permanently lock to the sleeve. When shaft 11 is locked in sleeve member 10 the two parts of the sleeve member are spread apart and knob 13 extends below and is secured by the bottom of sleeve member 10.
During use of the furniture, the motion of the furniture across the floor applies a lateral force to the roller. This force is especially significant when the furniture is pushed over rough surfaces such as concrete surfaces at the manufacturing facility, the storage location and sidewalks during delivery. Like forces are also created during abrupt movements of the furniture or when the furniture is pushed over objects on the floor. Such forces can occur even once the furniture is in the home or office where it is to be used. Similarly, when the furniture is pushed over thick carpeting, it incurs significant resistance to the movement and hence increased lateral forces on the caster assembly are created. All of these various types of forces create in effect a shock load on the caster assembly.
The lateral forces that are created are transmitted to shaft 11 and sleeve 10 that is positioned in hole 8, which applies pressure to the wooden support. If the force is large enough, shaft 11 and sleeve 10 can cause a splitting or cracking of the leg. Even if the force is not that abrupt or significant, the creation of the lateral force that is transmitted to shaft 11 and sleeve 10 over a period of time will cause the sleeve to enlarge the inner dimensions of hole 8 thereby causing the sleeve and hence the caster assembly to become loose from support 4. Retainer 14 provides little resistance to such lateral force and in fact serrated edges 15 can cause further splitting or cracking of the support. Consequently, such lateral forces that occur on the caster assembly during movement of the furniture eventually cause the casters to become loose and can also eventually damage the furniture itself.
While there are reinforcing plates per se disclosed within the prior art for preventing splitting of wood, there is no known assembly that avoids the above discussed problems. Such reinforcing plates are illustrated in U.S. Pat. Nos. 3,419,205 to J. C. Jureit and 3,480,305 to W. E. Jureit.